REA Registration and the Centro de Trabajo Notification: What to Arrange Before Work Starts in Spain
Guide for Foreign ContractorsYour company has secured a contract to carry out work in Spain, and the start date is already fixed. Before arranging for your team and equipment to arrive, you need to establish whether the work falls within Spain’s construction regulations and which formalities must be completed before work begins.
Delays often arise from the order in which requirements are addressed: who must notify the opening of the construction site, which regional authority is responsible, how the notification must be filed and which health and safety documents need to be ready. This guide explains the sequence and how to coordinate REA registration, the Subcontracting Book, worker posting and social security certificates, including the different documents relevant to UK and US employers.
When Do Construction Site Opening Requirements Apply in Spain?
Spain’s construction health and safety rules, set out in Royal Decree 1627/1997, cover obras de construcción: construction and civil engineering works, including refurbishment, repair, maintenance, demolition, excavation, earthworks and the assembly or dismantling of prefabricated components.
The rules can therefore also cover installation, equipment assembly and maintenance work where the activity forms part of construction work on site. The actual scope of the work must be assessed, including whether the company carries out physical works or only supplies equipment or provides remote supervision.
Two separate requirements must be assessed: the construction site opening notification and the posting of workers to Spain.
The site opening notification concerns the site as a workplace. It must be submitted by the business acting as contratista under Spanish construction law, regardless of the nationality of its workforce.
Worker-posting requirements concern employees temporarily sent to Spain by an overseas employer. The employer must assess the applicable posting obligations separately from responsibility for the site opening notification.
A company may be responsible for both requirements, one of them or neither, depending on its contractual role and workforce arrangements.
One Contact for Your Construction Site Requirements in Spain
Lawants identifies the obligations that apply to your project and manages or coordinates the required Spanish procedures: the centro de trabajo opening notification, REA registration, worker-posting formalities and the Libro de Subcontratación. Our legal and employment team adapts the work to your contractual role, site activities and workforce arrangements, with tax advice available where the project requires it.
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Construction Site Requirements in Spain: Five Key Compliance Checks
For a foreign contractor starting construction work in Spain, there are five core workstreams to assess:
- REA registration
- Notification of the opening of the centro de trabajo
- Worker-posting notification, where applicable
- Social security coverage certificate: an A1 certificate for qualifying UK postings, or a US Certificate of Coverage where the US–Spain agreement applies
- Libro de Subcontratación (Subcontracting Book), where the contractor subcontracts work
These requirements serve different purposes, although some can be handled through a coordinated filing route.
Where the special procedure in Royal Decree 1109/2007 applies to a foreign company posting employees to Spain under Law 45/1999, its first posting notification can also serve as an application for REA registration, accompanied by the prescribed declaration. That application provisionally allows the company to participate in subcontracting until registration is granted or refused. Under this specific regime, REA registration is not required for postings lasting no more than eight days. Eligibility for the procedure and exemption must be checked for the particular project.
Each requirement has its own responsible party and deadline. The table below explains what each procedure achieves, who is responsible and when it should be completed.
Five Core Requirements: Purpose, Responsibility and Timing
| Requirement | Purpose | Responsible Party | Timing |
|---|---|---|---|
| REA registration | Establish the company’s accreditation to work as a contractor or subcontractor | Companies subject to construction-sector registration rules | Before being engaged, subject to the applicable foreign-company procedure |
| Opening notification for the centro de trabajo | Notify the labour authority that site work will begin | The business acting as contratista | Before construction work starts |
| Worker-posting notification | Inform the authorities about employees temporarily sent from abroad | The overseas employer, where posting rules apply | Before the posting starts, subject to applicable exemptions |
| A1 or US Certificate of Coverage | Confirm which country’s social security legislation applies | The employer or worker, according to the applicable procedure | Apply before travel wherever possible; confirm eligibility and the period covered |
| Libro de Subcontratación | Record the subcontracting chain for inspection | The contratista that subcontracts part of the work | Before the first subcontract |
The requirements depend on the company’s role in the contracting chain, whether it sends its own employees and whether it subcontracts work. UK and US contractors must also assess the workers’ right to work in Spain, any relevant project permits and the company’s Spanish tax position before mobilisation.
In What Order Should You Complete the Requirements?
Once the applicable obligations have been identified, they need to be coordinated with the scheduled start date.
The sequence depends on your project: your role on site, whether employees will travel from the UK, US or another country, and whether you intend to subcontract any work.
The main bottleneck is often when a procedure is started and whether it is based on the correct requirements. REA registration, worker-posting formalities, digital identification and health and safety documentation can hold up mobilisation if they are addressed too late or based on incorrect advice.
Lawants identifies the critical steps, removes unnecessary requests and manages or coordinates the applicable formalities around your planned site start date.
The timeline below shows the general sequence. REA registration, worker posting and the Subcontracting Book apply only where the relevant conditions are met. For UK and US teams, the immigration and social security checks should begin early enough to meet the travel date.
Construction Site Opening Notification in Spain: The Centro de Trabajo
The site opening notification, known in Spanish as the comunicación de apertura del centro de trabajo, is a central administrative requirement before construction work begins. The key questions are who must submit it, when and where it must be filed, which filing route is available and what information the form requires.
Who Must Submit the Site Opening Notification?
Responsibility rests with the business acting as contratista under Royal Decree 1627/1997: the contractor engaged by the project client to carry out all or part of the works. The project client, called the promotor in Spanish law, must provide the contractor with the information needed to submit the notification correctly and on time.
Does a Subcontractor Have to Submit Its Own Notification?
Generally, no. The site opening notification remains the responsibility of the contratista; each subcontractor working on the same notified site does not file a separate opening notification. Subcontractors have their own obligations, including REA registration where applicable.
Project Clients, Self-Employed Workers and Temporary Joint Ventures
Where the project client also acts as contratista, it assumes the notification obligation in that capacity. For example, a client that directly engages self-employed individuals to carry out the works may be treated as the contractor in relation to those individuals and assume the associated duties. A specific exception applies to work commissioned by a private individual for their own home.
A site involving only self-employed individuals therefore still requires an assessment of who assumes the legal role of contratista within the actual contractual arrangements.
For a Unión Temporal de Empresas (UTE), a Spanish temporary joint venture, responsibility depends on who actually performs the works. If the UTE does not execute the works itself, each member company acts as contratista for the part it carries out, under Article 3(e) of Law 32/2006. The party responsible for the notification must be identified accordingly.
When Must the Notification Be Filed?
For construction works covered by Royal Decree 1627/1997, the notification must be submitted before work actually begins.
Which Spanish Authority Receives the Notification?
The notification is filed with the labour authority of the Autonomous Community, Spain’s regional administrative jurisdiction, where the site is located. Forms and filing arrangements can vary between regions. Checking the local procedure in advance helps avoid having to resubmit the notification.
Digital Certificates and Filing Routes for Foreign Contractors
Filing follows the procedure set by the relevant regional authority. Direct access to its online portal may require a recognised Spanish digital certificate. A company’s UK or US electronic signature credentials should not be assumed to provide access to a Spanish public-administration portal.
Some regional procedures require recognised digital identification for direct online filing; alternative arrangements may be available for foreign companies or through an authorised representative. For a site in Madrid, for example, the filing route and supporting documents should be checked with the Instituto Regional de Seguridad y Salud en el Trabajo (IRSST), the regional occupational safety authority, before submission.
Before starting the procedure, we confirm the filing channel accepted by the authority responsible for the particular site, including how a foreign company or its representative can submit the documents.
Foreign contractors must also arrange any necessary Spanish translations, adapt technical documents to the required forms, identify the business legally acting as contratista and coordinate the notification with REA registration where it is required.
What Information Does the Notification Form Require?
The official form, available from the relevant regional authority, contains Parts A and B. It requests:
- Project client details: the promotor must provide the information needed for the contractor to fulfil its notification obligation
- Details of the contractor, project designer and appointed health and safety coordinators
- Site information: expected workforce, description of the works, electrical installations and work equipment
Health and Safety Documents Required Before Construction Work Starts
Royal Decree 1627/1997 requires different safety documentation depending on whether the works have a formal construction project. Works with a project require an approved PSS; works without one require the relevant site-specific risk assessment.
Works with a Formal Project: ESS and PSS
Where the works have a formal project, the project client must arrange an Estudio de Seguridad y Salud (ESS, Health and Safety Study) or, where permitted, an Estudio Básico (Basic Health and Safety Study). Each contratista then prepares its own Plan de Seguridad y Salud (PSS, Health and Safety Plan), adapting the study to its activities and working methods.
The PSS sets out operational measures for preventing risks during the works. It requires approval before construction begins; an indemnity or liability waiver does not fulfil that function.
Who Approves the Health and Safety Plan?
Where a health and safety coordinator has been appointed for the execution phase, that coordinator approves the PSS. Otherwise, approval rests with the dirección facultativa, the professional team responsible for technical supervision. Public works follow a specific approval procedure involving the contracting public authority.
The approved plan must accompany the opening notification for the centro de trabajo.
Works without a Formal Project: Site-Specific Risk Assessment
For works without a formal construction project, the notification must be accompanied by the relevant site-specific risk assessment. It must address the actual tasks, equipment and auxiliary means to be used on the site.
From Document Review to Filing: We Manage Your Site Opening Notification
With the start date already fixed, project information, safety documents and approvals need to be coordinated before filing. The procedure, access route and forms depend on the Spanish region where the site is located.
Lawants checks what is missing, confirms the correct procedure and manages the site opening notification around the project timetable, coordinating related legal and employment requirements where needed.
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Ongoing Duties after the Centro de Trabajo Notification
After filing, two duties continue throughout the construction project.
Display the Notification on Site
The notification must remain displayed in a visible place on site for the duration of the works and be available for checks by Spain’s Labour and Social Security Inspectorate.
Notify Changes within Ten Days
Changes not identified in the original notification must be reported to the labour authority within ten days, under Article 3.5 of Order TIN/1071/2010. If the authority identifies defects in the submitted notification, the correction procedure follows Article 3.2 of the same Order. Failure to correct the notification within the prescribed period means it is treated as not having been submitted.
REA Registration and Posting Workers to a Construction Site in Spain
REA registration and worker-posting formalities have separate functions from the site opening notification. They may be procedurally linked where a foreign company qualifies for the route under Law 45/1999 and Royal Decree 1109/2007, allowing its first posting notification to serve as its REA application.
REA Registration for Foreign Contractors
REA registration applies to businesses working as contractors or subcontractors within the construction regime, subject to the relevant exclusions and special rules. Where the foreign-company posting procedure under Royal Decree 1109/2007 applies, the first posting notification and accompanying declaration can serve as the application, with provisional effect until registration is granted or refused. The eight-day exemption belongs to that specific regime and must be checked against the facts.
REA accreditation concerns the company and is separate from the opening notification for each centro de trabajo. Each obligation must be assessed and fulfilled where it applies.
Our dedicated REA guide explains when registration is compulsory, which requirements apply and how a foreign contractor can obtain an REA number in Spain.
Posting Workers to Spain: A1 and US Certificates of Coverage
If your company temporarily sends its own employees to Spain, assess the applicable worker-posting notification separately from the social security coverage certificate. For UK and US employers, the appropriate framework depends on where the employer is established, the workers’ coverage and the assignment arrangements.
- UK employers: for qualifying temporary assignments, an A1 certificate from HMRC confirms continued UK National Insurance coverage. Eligibility must be established for the assignment. See HMRC’s guidance on temporary work abroad.
- US employers: where the US–Spain Social Security Agreement assigns coverage to the United States, the relevant document is a Certificate of Coverage issued by the Social Security Administration. See SSA guidance for the US–Spain agreement.
Do UK and US Workers Need Permission to Work in Spain?
For UK and US nationals, the employer must separately establish the applicable immigration and work-authorisation requirements for the actual site duties, duration and individual circumstances. A social security certificate or worker-posting notification does not grant permission to work. Visa-free entry for a business visit should not be treated as authorisation to perform construction work. Any applicable exemption must be checked before travel.
Our guide to posting workers to Spain covers the notification process, supporting documents and applicable exclusions. UK and US projects also require the country-specific social security and immigration checks described here.
REA Registration Obtained in 24 Hours for a British Company
The contract was signed and the start date fixed, but an unnecessary preliminary requirement had delayed the project for weeks.
A British company engaged to carry out a temporary installation in Madrid had stalled its REA application after being told it first needed a Spanish NIF tax identification number. Reviewing the case established that a prior Spanish NIF was not required for that registration route.
We identified the requirements that actually applied, submitted the REA application and coordinated the worker-posting notification.
REA registration was obtained within 24 hours of filing, and the worker-posting formalities were completed during the same week, allowing site work to begin as scheduled.
Read the Case DetailsThese timings relate to the specific case. Outcomes and processing times depend on the available documents and the competent authority.
When Is a Libro de Subcontratación Required in Spain?
A contratista that intends to subcontract must obtain a Libro de Subcontratación (Subcontracting Book), authorised by the labour authority for the area where the works are performed, before subcontracting any part of the works. The duty attaches to the contractor that subcontracts work.
Authorisation and Recording Subcontracts
The book must record each subcontract with a subcontractor or self-employed individual in chronological order from the start of the works. It must remain available on site for inspection and enables the labour authority to monitor the subcontracting arrangements.
Retention and Inspections
Under Article 16 of Royal Decree 1109/2007, the contractor must keep the book on site until its assignment from the project client is fully completed. It must then retain the book for five years from the end of that contractor’s participation in the project.
Penalties for Failing to Submit a Site Opening Notification
Failing to submit the notification, or submitting inaccurate information, constitutes an infringement under Spain’s Law on Infringements and Penalties in the Social Order (LISOS). It is classified as minor where the activity is not considered dangerous, unhealthy or harmful (Article 11.3), and serious where it falls into one of those categories (Article 12.5).
The classification depends on the activity performed on the site and must be assessed for the particular project.
| Classification | Criterion | Fine Range |
|---|---|---|
| Minor | Activity not classified as dangerous, unhealthy or harmful | €45–€2,450 |
| Serious | Activity classified as dangerous, unhealthy or harmful | €2,451–€49,180 |
These ranges reflect the amounts in Article 40 of LISOS following the 20% increase introduced by Law 10/2021. The activity’s classification determines the applicable range; the seriousness of the infringement must be assessed against the actual site activities.
How Lawants Helps Foreign Contractors Start Work in Spain
Companies contacting us about a Spanish construction site usually have a fixed start date and several questions to resolve quickly: who must submit the notification, whether a posting notification is needed, how a foreign company can access the regional portal and what happens if a safety approval is missing.
Lawants provides a local team that checks your contractual role, identifies the correct regional procedure and coordinates the site opening notification, worker posting, REA registration and Subcontracting Book before the planned start date. Our legal and tax professionals can also address related issues arising from the company’s Spanish activity.
Our work includes:
- Reviewing the activities, contract and contracting structure
- Identifying the obligations that apply to the specific project
- Managing or coordinating administrative filings with the competent authority
- Checking consistency between REA applications, site notifications and worker-posting documents
- Supporting your company in dealings with the regional authority and coordinating technical documentation with the health and safety coordinator and the dirección facultativa, while those professionals retain their technical responsibilities
Your Site Has a Start Date. Get the Required Spanish Formalities in Place.
We help UK, US and other foreign contractors prepare for construction work in Spain. Our team reviews your contractual role and coordinates the site opening notification, REA registration, Subcontracting Book and worker-posting requirements through one English-speaking contact, with legal, employment and tax support matched to your project.
Tell us the site location, planned start date, your company’s contractual role, the work to be carried out and whether employees will travel from the UK, US or another country. These details help us give you a more useful initial response.
FAQs about Starting Construction Work in Spain
Answers to common questions from foreign contractors preparing to start work on a Spanish construction site.
What Is the REA in Spain?
The REA (Registro de Empresas Acreditadas) is the register for businesses working as contractors or subcontractors on construction projects. Registration demonstrates that the company has its own operational organisation, appropriately trained staff and compliant occupational risk-prevention arrangements. Applicable exclusions and the special procedure for qualifying foreign companies must also be considered.
Does a Subcontractor Need Its Own Site Opening Notification?
Generally, no. The duty rests with the contratista and is not duplicated for each subcontractor on the same notified site. Subcontractors have separate obligations, including REA registration where applicable.
Can a Worker-Posting Notification Also Serve as the REA Application?
Where the special foreign-company procedure applies, the first notification under Law 45/1999 can serve as the REA application under Royal Decree 1109/2007, accompanied by the required declaration. The eight-day REA exemption applies within that regime. Eligibility must be checked for the company and assignment; it is not a blanket exemption for every short construction project.
Does a Foreign Contractor Always Need a Spanish Digital Certificate?
The accepted filing route depends on the regional authority responsible for the site. Direct online access may require recognised digital credentials; an alternative route or filing through a representative may be available. Confirm the procedure before assuming your company needs its own Spanish certificate.
Must the Notification Always Include a Health and Safety Plan?
For works with a formal project, each contractor must provide its PSS and the corresponding approval. Works without a formal project require the relevant site-specific risk assessment covering the tasks, equipment and auxiliary means to be used.
What Happens if the Site Details Change after Filing?
Changes not identified in the original notification must be reported within ten days under Article 3.5 of Order TIN/1071/2010. Article 3.2 separately provides a ten-day period to correct defects identified by the authority in the submitted notification.
Does Every Company on Site Need a Subcontracting Book?
No. The duty applies to the contratista that intends to subcontract work. That contractor must obtain an authorised Libro de Subcontratación before subcontracting any part of the works.
